JP2009203853A - Lash adjuster in valve gear - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the change in a backlash amount during reassembly through the curtailment of contact pressure in a screw engagement part of the male screw and female screw formed by rolling. <P>SOLUTION: A female screw formed in a body is formed in a serrated shape, and threadedly engaged with a serrated male screw 25 formed on the outer periphery of a screw rod 24. A return spring 27 is assembled in the inside of a screw hole to urge the screw rod to a projecting direction from a screw hole opening end. The female screw and male screw are formed by a double-thread screw. When pushing force to the screw rod is loaded, contact pressure between the female screw pressure side flank and male screw pressure side flank contact part coming into contact with each other is reduced. A reference mark is provided to a part of the outer periphery of the body opening end. A matching mark is provided to the outer periphery of a screw rod screwing start end. When reassembling the lash adjuster, the matching mark is aligned with the referential mark to screw the screw rod therein. The female screw and male screw are threadedly engaged with the thread screws same as before assembly so that the change in a backlash amount is prevented. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a lash adjuster that automatically adjusts the valve clearance of a valve gear in an internal combustion engine.

  Valve operating devices that open and close an intake valve or an exhaust valve (hereinafter simply referred to as a valve) by rotating a cam include an arm type that pushes down the valve stem with an arm and a direct type that pushes down the valve stem with a cam. There are a swing arm type (end pivot type) and a rocker arm type in the valve operating device.

  Here, in the swing arm type valve gear, the end of the arm arranged below the cam is supported by a pivot, and the arm is swung around the pivot by the rotation of the cam. The valve stem is pushed down at the part to open the valve.

  On the other hand, in the rocker arm type valve gear, the arm is supported swingably around a rocker shaft provided above the cam, and one end of the arm is pushed up by the rotation of the cam, and the other end of the arm The valve stem is pushed down to open the valve.

  In any of the above valve gears, the valve clearance is automatically adjusted by incorporating a lash adjuster.

  Here, as the lash adjuster incorporated in the swing arm type valve operating device, the one described in Patent Document 1 is known, and as the lash adjuster incorporated in the rocker arm type valve operating device, the one described in Patent Document 2 is known. It has been. Moreover, what was described in patent document 3 is known as a lash adjuster built in a direct type valve operating apparatus.

  In any of the above lash adjusters, the male screw on the outer periphery of the screw rod is screw-engaged with the female screw of the screw hole formed in the body, and the screw rod is protruded from the screw hole by the return spring incorporated in the screw hole. Is energized.

JP 2005-273510 A JP 2006-132426 A JP-A-11-148320

  By the way, in the various lash adjusters described above, the male screw of the screw rod is a single thread, and if the single thread is formed by cutting, it takes time to manufacture and the cost is high, so the male thread is usually formed by rolling. Like to do.

  By the way, since it is difficult to form a high thread due to the workability of the male thread by rolling, the height of the thread is lower than the thread by cutting. For this reason, when the screw rod is pushed in and the pressure side flank of the female screw and the male screw come into contact with each other, the surface pressure at the contact portion is high, and the screw surface is easily worn. Further, the wear of the thread surface causes backlash between the screw engaging portions, resulting in inconvenience that vibration and abnormal noise are generated.

  In order to resolve this inconvenience, it is effective to use multiple threads for female and male threads. However, if multiple threads are used, the female and male threads will be undisassembled before product assembly, inspection, and reassembly after maintenance. There is a possibility that the thread is engaged with a thread different from the thread.

  Here, if the female screw and male screw are engaged with a different thread from the unassembled thread, the pressure-side flank may slip due to the poor compatibility of the pressure-side flank of the female thread and the pressure-side flank of the male thread. Burning may occur. In addition, the amount of backlash formed between the female screw and the male screw may change. In that case, the valve may be pushed up and compression leakage may occur.

  In general, if the amount of backlash formed between the internal thread and external thread differs among multiple cylinders among multiple lash adjusters installed per engine, there will be a difference in valve lift height and vibration will occur in the engine. Arise. For this reason, when assembling multiple lash adjusters, the lash adjusters with the same backlash amount are selected and assembled to the engine, but when reassembling the lash adjusters after maintenance, different thread screws are used. If the backlash amount is changed by screw engagement with the engine, vibration may occur in the engine.

  An object of the present invention is to provide a lash adjuster that adjusts a valve clearance by moving a screw rod having a serrated screw as described above in an axial direction at a screw engaging portion of a male screw and a female screw formed by rolling. It is to reduce the surface pressure and to prevent the backlash amount from changing during reassembly.

  In order to solve the above-described problems, in the present invention, a male screw formed on the outer periphery of a screw rod is screw-engaged with a female screw of a screw hole formed in the body, and the screw rod is screwed into the screw hole. A return spring that urges in the direction protruding from the blade is incorporated. In the lash adjuster in the valve operating apparatus in which the saw rod thread is provided with a lead angle that moves in the protruding direction while rotating the screw rod by pressing the return spring, the number of threads of the female screw and the male screw is plural, A reference mark is provided on a part of the outer periphery of the opening end of the body, and on the outer periphery of the screwing start end of the screw rod. Than it is adopted the configuration in which the mark each other to allow engagement of the same Article screws by the alignment with respect to the reference mark.

  Here, if the number of threads of the male thread and the female thread is two, the pressure side flank of one thread and the pressure flank of the other thread are arranged at symmetrical positions with the axis of the screw rod as the symmetry line. Therefore, when the screw rod is pushed in, the pressure-side flank of the male screw is wedge-engaged with the pressure-side flank of the female screw, and the wedge effect prevents slippage at the contact portion of the pressure-side flank, thereby reducing wear. A great effect can be obtained in the suppression.

  In addition, even when a moment load that tilts the screw rod due to the swinging of the arm is incorporated into the arm type valve gear, the moment load is reliably received by the contact portion of the symmetrically arranged pressure side flank. That is, it is possible to prevent the pressure side flank from being unevenly worn.

  In the lash adjuster having the above configuration, when reassembling after maintenance or the like, the alignment mark provided at the screwing start end of the screw rod is aligned with the reference mark formed on the body and screwed in, so that Screws can be screwed together.

  As a result, compatibility between each thread of the female screw and the male screw is maintained, and slippage at the pressure side flank can be prevented and wear can be suppressed. Further, since the amount of backlash formed between the female screw and the male screw does not change, the valve can be prevented from being pushed up.

  Further, since the backlash amount does not change, it is possible to prevent inconvenience such as engine vibration due to a difference in valve lift height between cylinders.

  In the lash adjuster according to the present invention, the reference mark and the alignment mark may be a line by scribing, or may be a punch hole formed by driving a punch. Further, it may be by stamping, by painting, or by sticking a seal.

  The lash adjuster according to the present invention may be for a swing arm type valve operating device, or may be for a rocker arm type valve operating device. Further, it may be for a direct type valve operating device.

  When used as a swing arm type valve operating device, a pivot part is provided at the tip of the screw rod located outside the body so as to swing one end of the arm in a swingable manner, and for a rocker arm type valve operating device. When using as a spherical surface, the tip of the screw rod located outside the body is provided with a spherical surface that comes into contact with the upper end of the valve stem.

  Furthermore, when using it for direct type valve gears, the body is cylindrical, provided with an end plate that comes into contact with the cam at the top, and provided with a screw hole into which the screw rod is screwed. A return spring is incorporated in the screw hole.

  As described above, in the present invention, when the screw rod is pushed in by making the number of threads of the female screw formed in the screw hole of the body and the male screw rolled on the outer periphery of the screw rod into plural, In addition, the pushing force can be received by the pressure side flank of each thread, and the surface pressure of the screw engaging surface can be reduced.

  For this reason, it is possible to suppress wear of the pressure side flank and to prevent generation of vibration and abnormal noise.

  In addition, when reassembling after maintenance, by aligning the mark with the reference mark and screwing the screw rod into the female thread, the threaded threads before disassembly can be screwed together. Compatibility between the two can be maintained, slippage at the pressure side flank can be prevented, and wear can be suppressed. In addition, since the amount of backlash formed between the female screw and the male screw does not change, the valve is prevented from being pushed up, and the valve lift height is different between the cylinders, resulting in the problem of engine vibration. It can be prevented in advance.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a swing arm type valve gear incorporating a lash adjuster according to the present invention. In the swing arm type valve operating apparatus, a lash adjuster A is incorporated in a fitting hole 2 formed in the cylinder head 1, and the roller 4 is placed in the middle of the swingable arm 3 supported at one end by the lash adjuster A. The roller 4 is rotatably supported, and the roller 4 is pushed down by the rotation of the cam 6 provided on the camshaft 5 to swing the arm 3, and the valve stem 7 is pushed down at the other end of the arm 3. The valve 8 provided at the lower end is opened.

  Here, the valve stem 7 has a spring retainer 9 at the upper end, and the valve stem 7 is attached in a direction in which the lower end valve 8 is in close contact with the valve seat 11 by the pressing force of the valve spring 10 loaded on the spring retainer 9. It is energized. A hemispherical spherical seat 12 is formed on the lower surface of one end of the arm 3.

  As shown in FIGS. 2 (I) and (II), the lash adjuster A has a columnar body 21 fitted into the fitting hole 2, and the body 21 has a screw hole 22 closed at the bottom. The male screw 25 formed on the outer periphery of the screw rod 24 is engaged with the female screw 23 of the screw hole 22.

  A spring seat 26 and a return spring 27 are incorporated in the screw hole 22, and the screw rod 24 is urged by the return spring 27 in a direction protruding from the upper end opening of the screw hole 22.

  A hemispherical pivot portion 24 a that supports the spherical seat 12 formed at one end portion of the arm 3 is formed at an end portion of the screw rod 24 that is located outside the upper end opening of the screw hole 22.

  Here, the thread of the female screw 23 of the screw hole 22 and the male screw 25 of the screw rod 24 is a sawtooth in which the flank angle of the pressure side flank 28 that receives the pushing force applied to the screw rod 24 is larger than the flank angle of the play side flank 29. The serrated thread is provided with a lead angle that moves in the axial direction while the screw rod 24 is rotated by pressing of the return spring 27.

  The male screw 25 of the screw rod 24 is formed by rolling. The male screw 25 is composed of a double thread, and the female screw 23 with which the male screw 25 is engaged is also a double thread.

  A backlash 32 is provided between each thread of the female screw 23 and the male screw 25, and the axial clearance (backlash amount) δ of the backlash 32 is the thermal expansion of the cylinder head 1 and the valve 8 when the engine is cold started. The size of the valve 8 can be prevented from being pushed up due to the difference.

  Here, the pushing-up of the valve 8 refers to a phenomenon in which the valve 8 is not completely closed and a compression leak occurs.

  In the assembled state, the lash adjuster A is subjected to a product inspection such as a matching inspection of the body 21 and the screw rod 24 and a measurement of a backlash amount. After the inspection, as shown in FIG. The reference mark 30 is attached to the outer periphery of the end portion, and the alignment mark 31 is attached to the outer periphery of the screwing start end portion of the screw rod 24. The alignment mark 31 is aligned with the reference mark 30, and the screw rod 24 is screwed. Thus, it is possible to engage with the same thread.

  Here, the fiducial mark 30 and the alignment mark 31 may be lines formed by scribing, or may be punch holes formed by punching. Further, it may be by stamping, by painting, or by sticking a seal.

  As the lash adjuster A, a product having the same backlash amount δ is selected after the product inspection, and is assembled to the engine.

  The lash adjuster A shown in the embodiment has the above-described structure. When the lash adjuster A is assembled to the swing arm type valve operating apparatus shown in FIG. When a clearance is generated between the rollers 4, the screw rod 24 moves in a protruding direction while rotating along the play-side flank 29 by pressing the return spring 27, and lifts the end of the arm 3 to absorb the clearance.

  Further, when the screw rod 24 receives a pushing force from the valve stem 7 via the arm 3, the screw rod 24 is filled until the axial screw gap formed in the screw engaging portion of the female screw 23 and the male screw 25 of the screw rod 24 is filled. Moves in the axial direction. When the pushing force is further applied, the pushing force is received by the pressure side flank 28 that is in pressure contact with each other, and the screw rod 24 is prevented from moving in the direction of immersing into the body 21 while rotating.

  On the other hand, when the distance between the upper end of the valve stem 7 and the camshaft 5 is shortened due to wear of the valve seat 11 or the like, the screw rod 24 is gradually increased due to the fluctuating axial load applied from the valve stem 7 via the arm 3. While being pushed and rotated, it moves toward the direction of immersing in the screw hole 22 of the body 21, and prevents the valve 8 from being closed incompletely when the valve 6 is closed when the base circle 6 a of the cam 6 contacts the roller 4. . At this time, the screw rod 24 is further pushed in by the screw gap from the position where the minimum value of the fluctuating load in the axial direction becomes 0, and does not move back further.

  On the other hand, in a steady operation state where adjustment of the valve clearance is not necessary, the screw rod 24 hardly rotates, and the axial direction formed between the screw engaging portions of the female screw 23 and the male screw 25 of the screw rod 24. Repeated axial displacement within the screw gap.

  As described above, in the lash adjuster A, when a pushing force is applied from the arm 3 to the screw rod 24, the pressure side flank 28 of the female screw 23 and the male screw 25 contact each other to receive the pushing force, and the screw rod 24 , While rotating, moves toward the direction of immersing in the body 21. When the surface pressure of the pressure side flank 28 that is in contact with each other is high, the pressure side flank 28 wears out and a backlash occurs between the screw engaging portions. Therefore, vibration and abnormal noise are generated.

  However, in the lash adjuster A shown in the embodiment, since each of the female screw 23 formed in the screw hole 22 and the male screw 25 formed by rolling on the outer periphery of the screw rod 24 is a double thread, the screw rod 24 is When pushed, the pushing force is received by the pressure side flank 28 of each thread, and the surface pressure of the screw engaging surface is compared with the case where the female thread 23 and the male thread 25 are one thread. It will be halved.

  For this reason, the pressure side flank is less likely to be worn, and it is possible to prevent the occurrence of vibration and abnormal noise due to the wear.

  Further, when the female screw 23 and the male screw 25 are double-threaded, the pressure-side flank 28 of one screw and the pressure-side flank 28 of the other screw are arranged at symmetrical positions with the axis center of the screw rod 24 as the symmetry line. become.

  For this reason, when the screw rod 24 is pushed, the pressure side flank 28 of the male screw 25 is wedge-engaged with the pressure side flank 28 of the female screw 23, and the wedge effect causes the contact at the contact portion of the pressure side flank 28. Slipping can be prevented and a great effect can be obtained in suppressing wear.

  The moment load that tilts the screw rod 24 by the swing of the arm 3 is applied, but the moment load is received by the contact portion of the pressure side flank 28 in a symmetrical arrangement, and the pressure side flank 28 There is no such thing as uneven wear.

  In FIG. 2, the internal thread 23 formed on the body 21 and the external thread 25 of the screw rod 24 are shown as double threads, but the number of threads is not limited to 2 but is 2 or more. I just need it.

  When the lash adjuster A is disassembled by maintenance, and the lash adjuster A is reassembled after the maintenance, the alignment mark 31 provided at the screwing start end of the screw rod 24 is aligned with the reference mark 30 formed on the body 21. Then, the screw rod 24 is screwed.

  As described above, by screwing the screw rod 24 with the alignment mark 31 aligned with the reference mark 30, the female screw 23 and the male screw 25 are thread-engaged with each other before disassembly, and the female screw 23. The compatibility between the thread threads of the male thread 25 and the male thread 25 is maintained. As a result, slippage at the pressure side flank 28 can be prevented and wear can be suppressed.

  Further, since the backlash amount δ formed between the female screw 23 and the male screw 25 does not change, the valve 8 can be prevented from being pushed up. Further, since the backlash amount δ does not change, it is possible to prevent the occurrence of inconvenience such as engine vibration due to a difference in valve lift height between cylinders.

  4 (I) and 4 (II) show a lash adjuster A for a rocker arm type valve gear. Here, in the rocker arm type valve gear, a roller 43 that is in contact with the cam 42 is rotatably supported at one end of an arm 41 supported so as to be swingable around the rocker shaft 40. The arm 41 is swung around the rocker shaft 40 by the rotation, and the valve stem 44 is pushed down at the other end of the arm 41 to open the valve 45.

  In the rocker arm type valve gear as described above, a fitting hole 46 is formed at the end of the arm 41 opposite to the upper end of the valve stem 44, and the lash adjuster A is incorporated into the fitting hole 46 to provide valve clearance. Adjust.

  Here, the lash adjuster A forms a screw hole 52 on the axial center of the cylindrical body 51 fitted and fixed in the fitting hole 46, and the internal thread 53 on the inner periphery of the screw hole 52 has a sawtooth shape. A serrated male screw 55 formed on the outer periphery of the screw rod 54 is screw-engaged with the serrated female screw 53, and a spring seat 56 and a return spring 57 are assembled in the screw hole 52. 54 is urged in a direction protruding from the screw hole 52.

  The lash adjuster A is assembled by fitting the body 51 into the fitting hole 46 of the arm 41 and pressing the valve stem 44 with the spherical surface 58 formed at the tip of the screw rod 54. When a pushing force is applied to the screw rod 54, the pushing force is received by the pressure side flank 59 in the screw engaging portion of the sawtooth female screw 53 and the sawtooth male screw 55. Reference numeral 60 denotes a play side flank.

  Also in the lash adjuster A, the number of threads of the female screw 53 and the male screw 55 is plural, and the surface pressure of the pressure side flank 59 that contacts each other when the screw rod 54 is pushed is reduced.

  Further, as shown in FIG. 4 (III), the reference mark 61 is formed on the outer periphery of the opening end of the body 51 so that the female screw 53 and the male screw 55 are screw-engaged with the same thread screw during reassembly after maintenance. And an alignment mark 62 is provided on the outer periphery of the screwing start end of the screw rod 54.

  5 (I) to (III) show a lash adjuster A for a direct type valve gear. Here, in the direct type valve operating apparatus, the valve stem 71 is pushed down by the rotation of the cam 70 to open the valve 72.

  In the direct type valve operating apparatus as described above, the lash adjuster A is incorporated between the cam 70 and the valve stem 71 to adjust the valve clearance.

  Here, the lash adjuster A has a screw hole in a bulging portion 82 a formed on the closed end plate 82 on the upper side of the cylindrical body 81 slidably fitted in a guide hole 74 formed in the cylinder head 73. 83, a female screw 84 on the inner periphery of the screw hole 83 is serrated, and a serrated male screw 86 formed on the outer periphery of the screw rod 85 is thread-engaged with the serrated female screw 84. A sling seat 87 and a return spring 88 are incorporated in the screw rod 85, and the return spring 88 biases the screw rod 85 in a direction protruding from the screw hole 83.

  The lash adjuster A is assembled so that the body 81 is slidable in the guide hole 74, a shim 89 overlapping the upper surface of the end plate 82 contacts the cam 70, and the tip of the screw rod 85 is the valve stem 71. When the pushing force is applied to the screw rod 85 by the rotation of the cam 70, the pushing force is applied to the pressure side flank 90 at the thread engaging portion of the sawtooth female screw 84 and the sawtooth male screw 86. I try to receive it. 91 indicates a play side flank.

  Also in the lash adjuster A, the number of threads of the female screw 84 and the male screw 86 is plural, and the surface pressure of the pressure side flank 90 that contacts each other when the screw rod 85 is pushed is reduced.

  Further, as shown in FIG. 5 (III), when the reassembly after maintenance, the female screw 84 and the male screw 86 are screw-engaged with the same threaded screw, as shown in FIG. A mark 92 is provided, and an alignment mark 93 is provided on the end face of the screwing start end of the screw rod 85.

Vertical front view of a swing arm type valve gear incorporating a lash adjuster according to the present invention (I) is sectional drawing which expands and shows the assembly part of the lash adjuster shown in FIG. 1, (II) is sectional drawing which expands and shows the screw engaging part of a female screw and a male screw Front view showing the state before the screw rod starts screwing (I) is a longitudinal front view of a rocker arm type valve operating apparatus in which a lash adjuster according to the present invention is incorporated, (II) is an enlarged sectional view showing a screw engaging portion of a female screw and a male screw, and (III) is The front view which shows the state before the screwing start of a screw rod (I) is a longitudinal front view of a direct type valve gear incorporating the lash adjuster according to the present invention, (II) is an enlarged sectional view showing a part of the lash adjuster, and (III) is (II) Bottom view of

Explanation of symbols

3 Arm 21 Body 22 Screw hole 23 Female screw 24 Screw rod 24a Pivot part 25 Male screw 27 Return spring 28 Pressure side flank 29 Play side flank 30 Reference mark 31 Alignment mark 44 Valve stem 51 Body 52 Screw hole 53 Female screw 54 Screw rod 55 Male screw 57 Return spring 58 Spherical surface 59 Pressure side flank 60 Play side flank 61 Reference mark 62 Alignment mark 70 Cam 71 Valve stem 81 Body 82 End plate 83 Screw hole 84 Female screw 85 Screw rod 86 Male screw 88 Return spring 90 Pressure side flank 91 Play side flank 92 Reference mark 93 Alignment mark

Claims (6)

A male spring formed on the outer periphery of the screw rod is screw-engaged with the female screw of the screw hole formed in the body, and a return spring for biasing the screw rod in a direction protruding from the screw hole is incorporated in the screw hole. The flank angle of the pressure side flank receiving the load in the pushing direction applied to the screw rod is made to be serrated so that the flank angle of the play side flank is larger than the flank angle of the play side flank. In the lash adjuster in the valve operating apparatus provided with a lead angle that moves in the protruding direction while the rod rotates,
The female screw and the male screw have a plurality of screw threads, a reference mark is provided on a part of the outer periphery of the opening end of the body, and the same thread is provided on the outer periphery of the screwing start end of the screw rod by alignment with the reference mark. A lash adjuster in a valve operating device, characterized in that an alignment mark that enables engagement with the valve is provided.   The lash adjuster in the valve gear according to claim 1, wherein the female screw and the male screw are double threads.   The lash adjuster in the valve gear according to claim 1 or 2, wherein the reference mark and the alignment mark are one of a marking line, a punch hole, a stamp, a paint application, and a sticker.   The lash adjuster in the valve operating device according to any one of claims 1 to 3, wherein the screw rod has a pivot portion at a tip end thereof that swingably supports one end of an arm of the swing arm type valve operating device.   The lash adjuster in the valve operating device according to any one of claims 1 to 3, wherein the screw rod has a spherical surface at a tip that is in contact with an upper end of a valve stem of a rocker arm type valve operating device.   The body is incorporated between the upper end of the cam and the valve stem disposed below the cam, and has a cylindrical shape that is supported so as to be slidable in the axial direction. The lash adjuster in the valve operating device according to any one of claims 1 to 3, wherein the lash adjuster is used for a direct valve operating device in which a screw hole into which the screw rod is screwed is formed in the end plate.

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